Abbildungen der Seite
PDF
EPUB

UNITED STATES DEPARTMENT OF AGRICULTURE

BULLETIN No. 723

Contribution from the Bureau of Entomology

L. O. Howard, Chief

and the Federal Horticultural Board, C. L. Marlatt, Chairman

Washington, D. C.

1

August 30, 1918

THE PINK BOLLWORM WITH SPECIAL REFERENCE TO STEPS TAKEN BY THE DEPARTMENT OF AGRICULTURE TO PREVENT ITS ESTABLISHMENT IN THE UNITED STATES.

By W. D. HUNTER,

In Charge of Southern Field Crop Insect Investigations and Member of the Federal Horticultural Board.

[blocks in formation]

In 1842 the superintendent of the Government cotton plantations at Broach, India, sent specimens of a very destructive cotton insect to the distinguished English entomologist, W. W. Saunders. The specimens were described as a new species, Depressaria (now Pectinophora) gossypiella, by Mr. Saunders in a paper presented to the Entomological Society of London on June 6, 1842 (9). This is thefirst published record concerning the insect which is now attracting so much attention in the principal cotton-producing countries of the world.

For 61 years after the publication of Saunders's description no published statement regarding the pink bollworm was issued. In 1904, however, an article was issued by J. Vosseler (10) regarding the great injury done by the insect in German East Africa. Within

1 Pectinophora gossypiella Saunders; order Lepidoptera, family Gelechiidae.
Numbers in parentheses refer to "Literature cited," p. 27.

63886°-Bull. 723-18--1

the next few years several additional articles dealing with the problem caused by the pest in German East Africa appeared. In 1909 D. T. Fullaway (5) published an account of the pink bollworm and its relation to cotton culture in the Hawaiian Islands, stating that it appeared to have been introduced from India within a very few years.

Only a few more or less technical papers were published from 1909 to 1913. Since the latter date a considerable literature has been built up, consisting largely of papers emanating from Egypt, where the pest has attracted increasing attention.

ORIGINAL HOME.

The original home of the pink bollworm is probably India and possibly Southern Asia generally, and its original host plants were the wild and cultivated cottons of that region. If this natural range of the insect extended to Africa it must have been limited to Central Africa and at least it did not extend to the Nile Valley region where cotton has been an important cultivated crop for a century or more. The occurrence of the insect in Egypt is apparently traced definitely to large shipments of seed cotton or imperfectly ginned cotton from India in 1906-7, and the spread of the insect from the points in the lower Delta near Alexandria, where this cotton was sent for reginning, throughout the Delta, and ultimately throughout Egypt, is so circumstantial as to leave no doubt as to the entry of the insect at that time into Egypt. With the first occurrence of the insect in Egypt it was confused more or less with other insects commonly found in cotton bolls in that country; and this confusion led to a statement by Dudgeon (4) that this insect had probably been in Egypt for many years. The careful investigation of the situation and determination of original points of infestation and spread by expert entomologists in the employ of the British and Egyptian Governments have fully disproved this early surmise and pointed out thi circumstantial introduction of the insect into Egypt as noted.

As already noted, the pink bollworm has been recorded as a cotto pest in India since 1842, and the original report made by the Superin tendent of the Government Cotton Plantation at Broach, India. of sufficient importance to be given in full, as follows:

The inclosed is an insect which was very destructive to the American corr which was sown here (Broach) on light alluvial soil. The egg is deposite in the germen at the time of flowering, and the larva feeds upon the cotton se until the pod is about to burst, a little previous to which time it has ope a round hole in the side of the pod for air, and at which to make an exit its own convenience, dropping on the ground, which it penetrates about inch, and winds a thin web in which it remains during the aurelia state. C ous enough, the cotton on the black soil was not touched by it. The nat cotton is sometimes affected by it.

The significant thing in the paragraph is the statement that the insect was very destructive to the American cotton and that "native cotton is sometimes affected by it." The fact that the American cotton was much more affected than the native varieties is in accord with the general experience with imported plants in relation to native plant pests, and with introduced pests in respect to native plants. The American variety was apparently unresistant in comparison with the native cottons of India which, with little doubt, had been long associated with this pest and which have developed a certain amount of resistance.

The later records of this insect show that it was reported from India on several occasions prior to 1900 or about that period, and those records determined also its occurrence eastward through Burma, Siam, and the Philippines, long prior to what was undoubtedly its original entry into Egypt in 1906-7.

The insect was first noted in Egypt in 1911, and the first severely infested field, one near Alexandria, was noted in the year following (1912). The increase of the damages from this insect in Egypt has been steady since 1912 and this in spite of very laborious and expensive control operations enforced by the Egyptian Government.

The present distribution, therefore, of the pink bollworm is reasonably traceable to spread from Southern Asia in comparatively recent years. The possible exception is German East Africa, and even there the natural explanation of its occurrence is its recent introduction with cotton imported from India, although there is the possibility, already noted, that the natural range of the insect may have included Central Africa and that the African infestation may therefore have come from such native stock.

PRESENT RANGE.

With the exception of two infestations in Texas, which it is hoped will be stamped out, the known range of the pink bollworm is as follows:

East Africa, West Africa, Egypt, Nigeria, Sudan, Zanzibar, India (very generally), Bengal, Ceylon, Burma, Straits Settlements, China, Philippines (Luzon), Hawaii, Brazil, and Mexico. There is also a record from Japan, although this may be erroneous. At any rate it is not confirmed by Prof. Kuwana, government entomologist, according to a statement published by Fullaway (5). The introduction of the pink bollworm into Brazil and Mexico is very recent, and the available records show very clearly how it was accomplished. As these are of special interest at the present time, the particulars will be given.

The information from Brazil comes through Mr. Edward C. Green, superintendent of the Cotton Department of the Ministry of Agricul

ture, who has published a very full statement on the subject (8). During 1913 Mr. Green made a trip of inspection through the greater portion of the cotton-producing area in Brazil. Special attention was paid to the seed, not only in the fields but in the ginneries, and no infestation was found. In 1916, however, another trip showed that the pink bollworm was present over wide areas in the States of Parahyba, Rio Grande del Norte, and Ceara. It seems that in the years 1911, 1912, and 1913, the Government of Brazil imported nine tons of Egyptian cotton seed. This seed was not fumigated as it was not suspected that any injurious insect was likely to be carried by it. A test for germination showed 89 per cent viable. It is altogether likely that a percentage of the unviable seeds were those attacked by the pink bollworm. All of this seed was sent to agricultural inspectors in various States and by them was distributed further throughout the cotton-growing districts.

There can be no doubt that the general establishment of the pink bollworm in Brazil was due to the importation of the Egyptian seed, and that incalculable losses to the country could have been avoided if proper quarantine precautions had been taken.

In Mexico the pink bollworm was introduced in 1911. During that season two importations of Egyptian seed were made. One consisted of 125 sacks and was planted near Monterey; the other, of 6 tons, and this was planted in the vicinity of San Pedro in the Laguna. From what is known of the abundance of the pink bollworm in Egypt in 1911 it is probable that both shipments of seed were infested and that both of them contributed to the present infestation in Mexico. It is true that cotton culture has not been continued in the vicinity of Monterey, but the crop of Egyptian cotton produced there in 1911 attracted considerable attention and much of the seed was shipped to the Laguna.

The work of determining the spread of the pink bollworm in Mexico was greatly facilitated by the cooperation of the Mexican Government. The Minister de Fomento, Sr. Pastor Rouaix, Sr. José Duvallon, Director de Agricultura, and Prof. Julio Requelme Inda of his department, showed the greatest interest in the matter as soon as the presence of the pink bollworm in Mexico was known. Sr. Duvallon dispatched a special representative, Sr. Alfonso Madariaga, to Northern Mexico, where he spent some months in making examinations in the Laguna. His findings corroborated in every way the discoveries made by Mr. Busck.

Very recently specimens of the pink bollworm have been received from China. They were collected by Mr. H. H. Jobson, who at the present writing (May, 1918) has just returned from China. Mr. Jobson's notes are as follows:

The collection which I have was secured from the seed room of one of the ginneries in Shanghai and from the fields at Tungchow, about 12 hours' ride by boat up the river from Shanghai. The infestation is more or less general throughout China; however, there may be some small areas where it is not present. A majority of the cotton grown within a radius of 100 miles of Shanghai is shipped into that port before being ginned, and from evidences found at the ginning establishments there is no doubt but what all those regions are infested. In fact, the larvæ are so numerous that by going into the seed room of the gins a person may secure any number of them within a very short time, as they may be seen crawling around over the seed and on the walls.

PRESENT DISTRIBUTION IN MEXICO.

As far as absolutely definite evidence shows, the pink bollworm is confined to three localities in Mexico, one of which is the Laguna district, a valley isolated by mountain ranges about 200 miles from the Texas border. The Laguna, in which the bulk of the total Mexican crop is produced, consists of about 1,200 square miles of land. Mr. August Busck, on a trip to Mexico in the early part of 1917, obtained samples of cotton seed from 40 of the estates in that region. Thirty of these samples were found to be infested and later records indicate infestation on ranches from which no insects in the seeds were received. In short it is evident that through the shipment of cotton seed from one part of the Laguna to another and possibly through the flight of the insect, the pink bollworm has become generally established there. Although the distribution of the pest is naturally irregular at the present time, it is certain that it will become uniform in the course of a few years, and that most energetic steps must be taken by the planters to control or eradicate the insect. Other localities known to be infested in Mexico are Allende, about 40 miles south of Eagle Pass, and the Trevino ranch, immediately opposite Del Rio. In both cases the infestations were the result of the receipt of seed from the Laguna.

NATURE AND AMOUNT OF DAMAGE.

The pink bollworm affects cotton production in several ways. In the first place it destroys a certain number of bolls or portions of bolls, in which case the lint produced is short and kinky (fig. 1). The injury, however, does not end with the reduction in the yield of lint. The crop of seed is correspondingly reduced, and what is obtained is of light weight and poor grade. In the crushing of Egyptian seed in England it was found that the oil content was lower than normal by about 20 per cent, and that the oil actually secured was of dark color and comparatively low value. The work of the insect is also of importance in connection with seed for plant

« ZurückWeiter »